Apparatus for chemically treating topped crude oil



June 23,1936. AE. PEw.JR 2,045,492

APPARATUS FOR GHEMICALLY TREATING TOPPED CRUDE 0.1L

original Filed July 29, 1952 Patented A June. 2,3-, 1936 PATENTN loEFicE APPARATUS FOR CHEMICALLY TREATING TOPPED CRUDE OIL Arthur E. Pew,Jr., Bryn Mawr, Pa., assigner to Sun Oil Company, Philadelphia, Pa., acorporation of New Jersey Original application July 29', 1932, SerialNo. 626,036. Divided and this application June 27 1933, Serial No.677,798

11 claims. I(el. 19a- 46) My invention relates to an apparatus adaptedfor carrying out the process, set forth in an application led by me andwhich has issued as Patent 2,006,407, July 2, 1935, for chemicallytreating topped crude oil to prepare it for distillation intov itsvarious lubricating fractions. Oi said application this application is adivision.

In the distillation of lubricating oils from topped crude oil it is ofthe utmost importance tov freev the stock charged to the lubricatingoil-still from any impurities which may be therein contained and whichare the results of cracking or oxidizing a portion of the crude whiletopping the same. Such cracked or oxidized compounds, if permitted toremain in the charging stock, will ulti- 'mately vaporize with thelubricating oil fractions during distillation, thereby making suchlubricating oils unt for sale without extensive chemical treatment, asthe cracked or oxidized compounds greatly impair the color, odor, etc.,of the distilled oil. It is also of the greatest importance to removeany water, whether naturally present in the crude or added thereto inprocesses for treating it to prepare it for distillation.

As some crudes are received from the -wells they contain, among otherimpurities, sodium, magnesium, and other chlorides. Some of thesechlorides are removed in solution when the water 'originally containedin the crude is settled out, but a small proportion of them` will remainin the crude. When the topped crude is subsequently treated with alkalisolution to remove cracked and oxidation products, the alkali used isacommercial form containing impurities in the form of chlorides. If thetopped crude is not thor-l oughly dehydrated after the alkali treatment,serious harm is likely to result, as the Water t0- gether with thenaturally present and added chlorides react, at the temperaturesrequired to distill lubricating oils, to form hydrochloric acid. Thisacid is extremely corrosive to the metal of the stills and for thisreason all water must be removed, 'for without it the chlorides cannotform hydrochloric acid and have no deleterious action on the stills. Itis necessary to treat the topped crude with an aqueous solution ofalkali in order to get a complete mixture and contact between the oiland alkali. If alkali in solid or comminuted form is added to the oil,a-complete mixture cannot be effected and the alkali settles out ontothe heating surfaces of the stills, thereby in a short time impairingheat exchange to such an extent that the stills must be shut down forcleaning. A I

A patent issued to me November 24, 1931, No.

1,833,691, and an application llled by me which has issued into Patent1,903,407, Apr. 4, 1933, are both directed to processes for dehydrating,topping, and then treating crude oil with an alkali solution in order toprepare the crude oil for distillation of the various lubricatingfractions contained therein. The present application is directed Amorespecifically to an improved apparatusor treating the topped crude oilwith sodiumhydroxide or other alkali solution and is especially adaptedfor the practice of the process forming lthe subject-matter of my Patent2,006,407.

sodium salts. I am also able to completely remove thewater, which isintroduced as a solvent for the sodium hydroxide,- from the mazootbefore distillation of the contained lubricating fractions. I am alsoable to remove, from the alkalitreated topped crude', all decompositionproducts which are precipitated bythe alkali treatment and subsequentdehydration.

In the drawing:

Fig. 1 is a front elevation with a sectionfof the towercut away; E

Fig. 2 is a section of the tower on line 2-2 of Fig. 1.

Thed heated topped crude or mazoot is continuously pumped to the mixingand evaporating tower 3 through line I. The crude, of which this mazootis a residuum, is ilrst freed of its contained salt water by heating andsettling under pressure after which'it is 'further heated in a pipestill, and thelighter constituents, such as gasoline, kerosene, and gasoil, vaporized in a distillation tower; The bottoms from thisdistillation tower, which comprise the mazoot to be treated by thepresent invention, leave the distillation tower and are pumped to theapparatus herein described at a temperature of 500 to 575 F.

The heated mazoot continuously enters the mixing pand in tower 3,tangentially thereof, so as to give it a whirling motion and is thereinmixed, for example, with 1% of`38 B. sodium hydroxide solutiom-which ispumped through line 2 and'iorced downwardly intothe whirling mazoot. Asthe mazoot-soda mixture overflows from the pan 4 it cascades over 'theseries nof 55 trays 5 and 8, which are supported on the uprights I.These uprights 'I also support the pan 4. As the mazoot-soda mixturecascades over the trays 5 and 6 the water, which acted as solvent forthe caustic soda, is vaporized, and some light oil fractions may also bevaporized with the water. Due to the high temperature of the mazoot(500575 FJ, the tower 3 may be maintained under a pressure above orbelow atmospheric or may be maintained at atmospheric pressure. However,since it is usually desired to evaporate as much of the water (sodasolvent) and as little oil as possible in the tower, the best workingpressure can be determined from these factors. The water and oil vaporspass upwardly through the tower 3 and then through line 8 to a condenserand separator (not shown). Safety valve 9 is providedvat the top of thetower to prevent the pressure from rising above any predetermined point.v

The soda-treated mazoot passes downwardly from the bottom of the towerthrough throat Ill to one end of a settling chamber II through which itows to the opposite end whence it passes through cross-overline I2 toone end of settling chamber I3.- At the opposite end, settling chamberI3 is connected to a third settling chamber I5 by cross-over I4. Afterflowing through chamber I5 the treated mazoot passes out of the systemthrough line I6.

Vapors are formed within the threesettllng tanks which, if permitted toaccumulate within the tanks, would by their pressure lower the,level ofthe liquid within the tanks to a point below the cross-over lines I2 andI4, thereby preventing an even ow of mazoot. For this reason tanks I3and I5 are provided with domes I1 and I8 respectively, which areconnected to pressure equalizing line 2| by pipes I9 and 20respectively. Any difference in pressure within the three tanks isequalized by the line 2|. Connections 22 and 23 are placed between line2| and vapor line 24, which conveys any vapors generated within thetanks to the top o f the tower 3. The provision of vapor line 24obviates the necessity of the vapor passing into the throat betweentower 3 and tank II and then up against the downwardly ilowing sodatreated mazoot. At times the settling mazoot may foam due to the rapidformation of vapors in the settling tanks, in which case the foam passesover pipe 2| to the throat between tower 3 and tank II and is beatendown` by the falling mazoot.

During the passage of the soda treated mazoot through the settling tanksII, I3 and I5 certain sodium salts, formed by the action of the causticsoda on the cracked and oxidation compounds present in the topped crude,are precipitated. These sodium salts settle to the bottoms of the tanksand are drawn off at intervals through valved outlets 25; 26 and 21, atthe center of the respective tanks. Each of these outlets is connectedto a manifold 28, which in turn is connected to pump 40 by line 39.These sodium compounds are of such a nature that they are liable to packsolidly in the bottoms of the tanks II, I3 and I5 and thereby stop upthe outlets 25, 26 and 21. For this reason there are provided two otherdraw-off pipes in each tank, one draw-off being positioned at each endof the tank. These draw-offs extend downwardly from near the top of thetank to within a few inches of the bottom so that there is no likelihoodof their being stopped up by tightly packed sludge. The draw-oils justdescribed, which are placed in the front -of the settling tanks, arenumbered 29, 3| and 33. Draw-ois 29 and 3| are connected to pipe 4|,which is provided with valves for controlling the now from each tank.Pipe 4| is connected to pump 4|! by lines 35, 3l and 39. The 5 frontdraw-oil 33 in tank I5 is connected to pump 4|! byA lines 42, 43, 35, 31and 39. This draw-o is also provided'wlth a valve in line 42 to regulatethe outflowI of sludge. The rear drawoffs are located directly to therear of the front l0 draw-offs and are numbered 30, 32 and 34. Thesedraw-o's are also provided with control valves and connecting lines topump 40. Line 36 corresponds to' line 35 in the front draw-off systemand connects through lines 31 and 39 to l5 pump 40 while lines 45 and'46correspond to lines 42 and 43 in the front of the tank. It is readilyseen that with the arrangement just described, any one sludge draw-oilmay be used if more sludge should collect in any one tank 'than in 20the others, or all sludge draw-offs may be used at once. l

The oil is 4thus thoroughly dehydrated, thereby preventing the formationof hydrochloric acid, the destructive eiects of which have beenhereinbefore explained.

It has been specied herein, by way of an example, that 1% of 38 B.caustic soda solution is admixed .with the mazoot. The necessary amountof the soda, however, varies with different crudes. The caustic soda, isnot added to treat the mazoot solely in the `step of preparingmazoot'for distillation into lubricating4 oils herein described, but isalso added so that there will be a surplus of free alkali left inthe oilto react 35 with any cracked or oxidation compounds which may formduring the actual distillation. For this reason enough caustic soda isadded, in the process herein described, so that about 2%V of free alkaliremains in the asphalt bottoms after the lubricating fractions have beenremoved or dis- -tilled oft. The free alkalileft in the topped crude isso finely divided, due to the intimate mixture possible when it is addedin aqueous solution, that it will not settle out onto the heatingsurfaces of the stills.

It is ordinarily desirable, in tower 3, to -vaporize only the solvent(water) of the' alkali. However, some light oil fractions are likely toevaporatewith the water; and it may be desirable, under some conditions,to vaporize in the tower, in addition to the water, an intermediate orfinal cut of gas oil or alight fraction of lubrication oil.

What I claim and desireto protect by Letters Patent is:

v1. Apparatus for alkali treatment of topped crude oil comprising atower and a settling tank, a mixing pan within the tower, oil and alkalisolution inlets to the pan, a series of trays also within the tower butbelow the mixing pan, a 60 vapor outlet from the tower above the pan, anoil passage from the tower to the settling tank,

a sludge outlet from the settling tank and an oil outlet from thesettling tank.

2. Apparatus for alkali treatment of topped crude oil comprising a towerand a plurality of settling tanks, a mixing pan withinY the tower, oiland alkali solution inlets to the pan, a series of trays also within thetower but below the mixing pan, and a vapor outlet from said tower abovethe pan, a passage for treated oil from the tower to the settling tanks,means for equalizing the vapor pressures in the tanks, sludge outletsfrom the settling tanks and oil outlets from said settling tanks.

3. Apparatus for alkali treatment of topped crude oil comprising a towera plurality of settling tanks arrangedlin series, a mixing pan withinthe tower, oil and alkali inlets to the pan, a series of trays withinthe tower but below the pan, a vapor outlet from the tower above thepan,

a treated-oil passage from the tower to the iirst of the series ofsettling tanks, treated-oil passages between'the settling tanks, anoutlet for treated oil from the last tank in series, and sludgedraw-offs from the settling tanks.

4. Apparatus for treating topped crude oil preparatory to distillationof lubricating oils, which comprises an evaporating tower wherein thesolvent of the alkali of a mixture oi oil and an alkali solution isadapted to` be vaporized, a series of settling tanks through whichthe'treated mixture is adapted to successively flow, means aording anoil flow passage from the evaporating tower to the first tank of theseries, outlets for settled sludge from each tank, an oli outlet fromthe last tankof the series, vapor outlets from the settling tanks beyondthe rst tank of the series, and a vapor line connecting said outletswith said passage.

5. Apparatus for alkali treatment of topped crude oil comprising asolvent evaporating tower; a plurality of settling tanks arranged inseries;

a vapor outlet from the tower; a passage for' treated oil from the towerto the rst of the series of 4settling tanks; passages for treated oilbetween the settling tanks; and a plurality of sludge draw-offs fromeach tank, one draw-off having an inlet openingI into the bottom part ofthe tank and extending therefrom through the tank bottom and throughwhich solids are adapted to be drawn oil? at intervals and anotherdrawoi having an inlet end opening into the tank above its bottom andextending therefrom upward, and pumping means for forcibly removingsludge from the last named draw-oils.

6. Apparatus ,for alkali treatment of topped crude oil comprising asolvent evaporating tower, a plurality of settling tanks arranged inseries, a vapor outlet from the tower, a treated-oil passage irom thetower to the first of the series of settling tanks, treated-oil passagesbetween the settling tanks, a treated-oil outlet from the last tank inseries, sludge draw-oils from the settling tanks, and vapor passagesestablishing v communication between the said oil passage, the settlingtanks and the upper part of the tower.

7. Apparatus for settling precipitated matter from alkali treated toppedcrude oil comprising a plurality of tanks so connected that the oiicontaining the material to be settled iiows from end to end of each tankand then to the next tank in series; an oil inlet to the rst tank of theseries; an oil outlet from the last tank of the series; sludge draw-ous,one draw-off having an inlet opening into the bottom part of the tankand extending therefrom through the tank bottomand vent.

ough ch solids are apted to be drawn o at in w and another draw-ouhaving an inlet end opening into the tank above its bottom and extending'therefrom upward, and means for equalizing the vapor pressure withinthe tanks. 5

8. Apparatus for settling precipitated matter from alkali treated toppedcrude oil comprising a plurality oi' tanks so connected that the oilcontaining the material to be settled ows from'end to end of each tankand then to the next tank in series; an oil inlet to the nrst tank ofthe series; an oiloutlet from the last tank of the series; sludgedraw-ois, one set extending downwardly from the bottom of each tank andanother set extending upwardly from near the bottom of each l5 tank;means for removing vapors generated in the tanks; and means forequalizing the vapor pressures withinthe tanks.

9. Apparatus for treating topped crude oil preparatory to distillationof lubricating oils, which 20 comprises an evaporating tower lwhereinthe solvent ot the alkali of a mixture of oil and an alkali solution isadapted to be vaporized, a settling tank, adapted to receive from thetower the dehydrated mixture and provided with an outlet for oil and 25an outlet for settled sludge, a vapor ofitake from the evaporator and avapor ofttake leading from the settling tank to a point in theevaporator above the locus therein of vaporizaton of said sol- 10.Apparatus .for treating topped crude oil preparatory to distillation oflubricating oils, which comprises an evaporating tower wherein thesolvent of the alkali of a mixture of oil and an alkali solution isadapted to be vaporized, means 35 to separately admit the oil and thealkali solution to a locus d! mixing within they tower, a settling tankadapted to receive from the tower the dehydrated mixture and providedwith an outlet for oil and an outlet for settled sludge, a vapor offtakefrom the evaporator and a. vapor oil'takeI leading fromv the settlingtank' to the evaporator at a. level therein above that of the points ofadmission thereto of the oil and the alkali solution. f

11. Apparatus for' treating topped crude oil preparatory tovdistillation of lubricating oils, which comprises an evaporating towerwherein the solvent of the alkali oi a mixture of oil and an alkalisolution is adapted to be vaporized, a settling tank, into whichhydrated oil is adapted to ow from the tower, said settling tank beingprovided with a low outlet for withdrawal of settled sludge, an oiloutlet and a vapor outlet above the oil outlet, a pipe connected withthe vapor outlet and through which any oil foam carried of! with thevapors through said vapor outlet is adapted to be conveyed to the oilstream from the tower and thus returned to the settling tank, and avapor pipe adapted to carry ou vapor escaping from said vapor outlet.

ARTHUR E. PEW, Jn.

